Apparatus for making radiographs



March 15, 1938. G. GROSSMANN 2,

APPARATUS FOR MAKING RADIOGRAPHS Filed Jan. 8, 195s 2 sheets-sheet 1 Fig. 1 F1192 March 15, 1938.

G. GROSSMANN APPARATUS FOR MAKING RADIOGRAPHS Filed Jan. 8, 1956 2 Shets-Sheet 2 Patented Mar. 15, 1938 UNITED STATES 2,110,954 7 APPARATUS roa MAKING RADIOGRAPHS Gustav Grossmann, Berlin-Zehlendorf-West Germany Application January 8, 1936, Serial No. 58,170 In Germany January 9, 1935 2 Claims.

This invention relates to a method of and apparatus for making radiographs of sections of objects or bodies, in which the radiograph of the section shall appear sharply, free from interfering shadows caused by objects or parts located upon either side of the plane of the section to be radiographed.

The invention and its aims and objects will be clearly understood from the following description of one illustrative embodiment of my invention shown in the accompanying drawings, the true scope of the invention being pointed out in the appended claims.

In the drawings:

Fig. 1 is a front elevation, largely diagrammatic of one illustrative form of apparatus for practising my invention, certain parts being shown in section and the X-ray tube and X-ray sensitive layer holder being shown in their median position;

Fig. 2 is a lateral elevation also largely diagrammatic and with certain parts in section, of the illustrative form of apparatus shown in Fig. 1;

Fig. 3 is a diagrammatic front sectional elevation, similar to Fig. 1 but with the X-ray tube and X-ray sensitive layer holder in one end position, that is to say at one extreme limit of their stroke;

Fig. 4 is a diagram illustrating the rectilinear movement of the Xray focus and X-ray sensitive layer, and how said movement obliterates or effaces, for all practical purposes, any interfering shadows that might be projected by objects or parts situated at either side of the plane of the section being radiographed, so that a sharply defined picture of said section results;

Fig. 5 shows diagrammatically one illustrative form of automatic means for turning the X-ray tube on and off.

Referring to the drawings and the illustrative embodiment of my invention therein shown, a rigid support, such as a supporting table 2 supports a carriage 4 forming a container or holder for the X-ray sensitive layer or film 6 and preferably also for a scattered ray grid diaphragm 8. Said carriage is carried on four rollers III which are preferably guided in parallel guide grooves l2 directed at right angles to the plane of Fig. 2. To each of the four corners of said table 2 is secured an upright standard l4, said four standards being joined at their upper ends by connecting members N5, of which the two extending at right angles to the plane of Fig. 2 are provided with guide grooves l8, it (see Fig. 2) parallel to said guide grooves I2 and serving to guide rolls 20, 20 supporting an X-ray tube housing 22 in which is mounted an X-ray tube 24.

The object (human body for example) of which a section is to be radiographed is diagrammatically indicated at 26 in Fig. 1. It rests upon a suitable supporting surface which may be vertically adjustab1e,'such as the top of a table 28 for example, having vertically adjustable legs so for the adjustment of which any conventional adjusting means, such as screw-threaded connections 32 may be used. The supporting surface extends between the lateral standards l4 and between the X-ray tube housing 22 and the carriage 4 containing the X-ray sensitive layer 6, and parallel to said layer.

In Fig. 1 the carriage 4 and the X-ray tube housing 22 are in their median position, so that the main or central ray of the X-ray or beam tube 24 will pass through the center M of the object or body 2Bxof which a section a-b for example is to be radiographed, and also through the center N of said X-ray sensitive layer or film fi contained in said carriage 4.

In addition to being movable rectilinearly with its housing 22 along the guide grooves It, It, said X-ray tube 24 is mounted in said housing for rocking or turning movement with its conical shield 34 about an axis g-h directed at right angles to its path of rectilinear movement.

The scattered ray diaphragm 8 will preferably be of the grid type and the grid elements 36 will preferably be parallel to the path of rectilinear movement of said X-ray tube 24 and carriage 4 (see Fig. 2).

In accordance with the present invention, to make a radiograph of a section, the X-ray tube 24 and the X-ray sensitive layer holder are moved rectilinearly in unison and parallel .to each other in'opposite directions from one end or terminal position to the other during the making of the exposure, and the X-ray tube is at the same time rocked about said axis g-h. These movements are so coordinated that the projection of any point of a body section being radiographed and located in a 'plane a-b for example, will during the entire continuance of the exposure always be projected upon the same point of the Y-ray sensitive layer, whatever the position of the X-ray tube focus; or, in other words, said movements of the X-ray tube and X-ray sensitive layer are .so coordinated that the picture of the section being radiographed will throughout the dura- ,tion of the exposure always be projected upon the same portion of the X-ray sensitive layer,

thus insuring a sharply defined radiograph of said section.

The invention contemplates the provision of any suitable means for accomplishing this result. In the illustrative embodiment of the invention herein shown said means may conveniently comprise a positive connection between said X-ray tube and X-ray sensitive layer as follows: Two links 38, 40 are pivotally connected, the former to the carriage 4 and the latter to the X-ray tube housing 22. These pivotal connections may conveniently comprise arms 42, 44. rigidly connected at one end to said carriage 4 and housing 22, respectively, and having their free ends pivoted at 46 and 48 to said links, respectively. Link 38 has a sliding fit in a sleeve 50 which is rotatable about a shaft 52 carried by a member 54 square in cross-section, and having a sliding fit in a guide 56 of corresponding cross-section and provided with a vertical longitudinal opening for the passage of said shaft 52. Said guide 56 is rigidly connected to said table 2, and said member 54 is adjustable vertically relatively thereto, for example by means of a screw-threaded connection 58 between said member 54 and said guide 56. This provides for vertical adjustment of said shaft 52 and therefore of the axis of rotation of said link 38, to enable said axis to be positioned in the plane of the body section to be radiographed, as shown in Fig. l. Links 38 and 40 are slidable longitudinally relatively to each other. This may conveniently be provided for by a telescopic connection 60, for example, between said links.

It will be apparent that movement of the X- ray tube in one direction will, through the positive connections described, move the X-ray sensitive layer in unison with said X-ray tube but in the opposite direction.

Means are provided for rotating or rocking said X-ray tube about said axis g--h so as to cause the main X-ray beam to be directed constantly through the same point M of the section being radiographed, during the longitudinal movement of said X-ray tube in making an exposure. Any suitable means may be provided for this purpose without departing from the scope of the invention. Herein said means illustratively comprises an arm 62, rigidly connected to said X-ray tube and pivotally connected at 64 to one end of a link 66, the other end of which may be pivotally connected at 68 to an extension 10 of said link 40. The X-ray tube housing 22 is provided with two openings 12 and 14 through which the arm 62 and the conical X-ray tube shield 34 extend respectively and which are suitably shaped to permit the necessary swinging movements of said arm 62 and shield 34. I

In operation, the shaft 52 having been adjusted to position it in the plane of the body section to be radiographed, it will be seen that if the link system comprising links 38, 40 be swung about said shaft 52 in the direction of the arrow, Fig. 1, either by hand or by any suitable driving mechanism, the X-ray tube housing 22 will be moved from its median position in Fig. 1 into its left terminal position shown in Fig. 3 and the X-ray sensitive layer and scattered ray grid diaphragm will simultaneously be moved in unison with said X-ray tube from their median position shown in Fig. 1 into their right hand terminal position shown in Fig. 3, said X-ray tube being simultaneously rocked about its axis gh in unison with and during said movements, so that the main X-ray beam will constantly be directed during said movements through substantially the same point M of the body section being radiographed.

As the shaft 52 is adjusted so as to be positioned in the plane of the body section to be radiographed, the displacement of the picture-receiving X-ray sensitive layer will stand in the same ratio to the displacement of the X-ray tube focus in the opposite direction as the distance of the section to be radiographed from said X-ray sensitive layer 6 is to the distance of the plane ab from the plane cd within which said X-ray tube focus moves. Consequently the projection of any point in the plane a-b must always fall upon the same point of the X-ray sensitive layer in every positionof said focus.

In making a radiograph the X-ray tube and the X-ray sensitive layer are moved from one end or terminal position to the other. Referring to Fig. 4, F and F indicate the end positions of the X- ray tube focus, which is moved from F to F in making the exposure. When said focus is located in F the arrow k-Z, representing the body section to be radiographed, will be projected and pictured upon the X-ray sensitive layer at k Z said X-ray sensitive layer being in the position I. If the X-ray tube be moved through the distance F F to the other terminal position, the X-ray sensitive layer will be moved in unison therewith in the opposite direction to the position 2 and the projection or picture of the body section to be radiographed will move with said X-ray sensitive layer as a unit from the position k l to the position k l That is to say, during the whole of said movement the projection or picture of the section to be radiographed will remain in the same position upon said X-ray sensitive layer and consequently will be sharply pictured upon the latter. On the other hand the projections or pictures of all parts or objects located in the body the section of which is being radiographed at either side of the plane of said section, that is to say outside of said plane, such as the point p and cross 0, for example, projected upon said X- ray sensitive layer at p and when the X-ray tube is at F will during said movements of the X-ray tube and X-ray sensitive layer, move relatively to said X-ray sensitive layer from p to p and o to 0 being thus projected successively upon constantly changing parts of said X-ray sensitive layer. They will thus be blurred and for all practical purposes washed out or eifaced, leaving a perfectly clear and sharply defined picture of the body section radiographed.

In similar apparatus heretofore used it was believed advantageous to make the path or stroke of the point of emission of the X-ray as long as possible, it being supposed that interference shadows could be the more eificiently eifaced, the longer the path'of said focus, other things being equal. It has therefore been proposed to move the path of emission of the X-ray in a path, the vertical projection of which upon the plane of the body section to be radiographed is a curve of two dimensions, such as an Archimedes spiral. This,

however, is true only of interfering shadows of minimum length, 1 to 2 mm, for example. In practice, however, interfering shadows of much greater length must be efliciently eifaced. Applicant found that the greater the area of the inter fering shadows the more diflicult it is efficiently to efiace them and that movement of the point of emission of the X-ray along a curve of two dimensions gives rise to additional extremely dark or complete shadows where the area of the interfering shadows is considerable, said extremely dark ated in a plane perpendicular to the body section to be radiographed and therefore represented by -a straight line in plan view, the main X-ray beam during said movement always passing through the same point of the body section to be radiographed. This offers the great technical advantage that in making radiographs of sections of moving organs a scattered ray grid diaphragm can be used with the same advantage as in making stationary radiographs.

It has been proposed to move the X-ray tube focus along a straight line in a plane parallel to the plane of the section tobe radiographed, the X-ray tube remaining parallel to itself during such movement, so that consequently the main X-ray beam always remains parallel to itself. This mode of procedure, however, proved impracticable, for the following reasons: The opening of the effective cone of light in a band focus diaphragm, which is the only kind that can be used in practice if the required sharpness of definition is to be obtained, is no greater than 31.- It therefore encloses only a limited area of the body section to be radiographed. If the stroke of the X-ray tube focus be made so great as is required for a sufficient obliteration of interfering shadows, only certain parts of the body section being radiographed will be found at any one time within the effective cone of light, as it moves parallel to itself during the making of the exposure. The radiograph obtained is therefore not uniformly exposed throughout its entire area. In order that this may be so it is necessary that the entire section area to be radiographed shall be traversed by effective X-ray beams, that is to say included within the effective cone of light, during the entire duration of the exposure. This can only be accomplished if the stroke of the X-ray tube focus be quite short. If, for example, a circular area, say cm. in diameter of a body section is to be radiographed, then the X-ray tube focus cannot be moved more in all than 8 cm., where the distance of the X-ray focus from the body section is '75 cm.; that is to say, the stroke of the X-ray tube focus cannot exceed 4 cm. If the stroke be greater the circular area 20 cm. in diameter will not be within the effective cone of light during the whole duration of the exposure. A 4 cm. stroke of the X-ray tube focus, however, where said focus is distant cm. from the body section to be radiographed will not nearly suflice to efface interfering shadows sufficiently. In such apparatus heretofore used it was therefore necessary to limit the pictures to small sizes or else be content with an insufficient obliteration of interfering shadows.

The present invention overcomes all these disadvantages in that the X-ray tube, while being moved rectilinearly during the making of the exposure is simultaneously turned or swung about an axis perpendicular to the path of said rectilinear movement, in such manner that the main X-ray beam throughout said movement always passes substantially through the same point of the body section being radiographed, and as shown in Fig. 4, the entire body section area which it is desired to radiograph remains within the effective cone of X-rays and will be traversed by said effective rays, during the entire duration of the exposure. The X-ray may be turned on and off by hand or this may be done automatically by any suitable conventional means.

Said housing 22 and said carriage 4 may also be permitted to oscillate back and forth during the making of the exposure. If it is desired to radiograph a different section than section a-b, a higher one e-'j for example, the member 54 will be adjusted vertically to locate the shaft 52 in the plane of the section to be radiographed, section ef for example. The best radiographs of body sections are obtained when the movement of the X-ray tube and X-ray sensitive layer are perpendicular to the longitudinal axis of the body, a section of which is to be radiographed. For this reason the body supporting table 2 is so positioned that its longitudinal axis is perpendicular to the direction of said movements.

It will be apparent that the apparatus embodying the invention could be turned 90 in order to adapt it to make radiographs of standing patients.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim:

1. Apparatus for making radiographs of body sections, comprising a rigid suport; an X-ray tube carriage and a film carriage movable in rectilinear parallel paths upon said support at opposite sides respectively of the body to be radiographed, during the making of the exposure; an X-ray tube mounted for swinging movement upon said X-ray tube carriage; an extensible two-armed lever having one arm pivotally connected to said X-ray tube carriage and to said X-ray tube, respectively, and the other arm pivotally connected to said film carriage; a shaft located between said two carriages and about which saidv twoarmed lever is adapted to be swung, the swinging movement of said X-ray tube upon its carriage being about an axis that is perpendicular to the plane in which said lever is adapted to swing and parallel to said shaft, whereby swinging movement imparted to said lever about said shaft will move said X-ray tube carriage and said film carriage in opposite directions along their respective rectilinear paths and simultaneously will swing said X-ray tube about its said axis in unison with its rectilinear movement to direct the main X-ray beam always substantially upon the same point of the body section to be radiographed throughout the making of the exposure; and

means to adjust said shaft relatively to the body section to be radiographed.

2. Apparatus for making radiographs of body sections comprising a rigid suport; an X-ray tube carriage and a film carriage movable in rectilinear parallel paths upon said support at opposite sides respectively of the body section to be radiographed, during the making of the exposure; a scattered X-ray grid diaphragm carried by said film carriage and having its grid elements extending parallel to the direction of said rectilinear movement of said carriages; an X-ray tube mounted for swinging movement upon said X-ray tube carriage; an extensible two-armed lever having one arm pivotally connected to said X-ray tube carriage and to said X-ray tube, respectively, and the other arm pivotally connected to said film carriage; a shaft located between said two carriages and about which said two-armed lever is adapted to be swung, the swinging movement of said X-1-ay tube upon its carriage being about an axis that is: perpendicular to the plane in which said lever is adapted to swing and parallel to said shaft, whereby swinging movement imparted to said lever about said shaft will move said X-ray tube carriage and said film carriage in opposite directions along their respective rectilinear paths and simultaneously will swing said X-ray tube about its said axis in unison with its rectilinear movement, to direct the main X-ray beam always substantially upon the same point of the body section to be radiographed, throughout the making of the exposure; and means to adjust said shaft relatively to the body section to be radiographed.

GUSTAV GROSSMANN. 

